Hormonal intrauterine devices and heat exchange during exercise.

Synthetic progestins in oral contraceptives are thought to blunt heat dissipation by reducing skin blood flow and sweating. However, whether progestin-releasing intrauterine devices (IUDs) modulate heat loss during exercise-heat stress is unknown. We used direct calorimetry to measure whole-body total (dry + evaporative) heat loss in young, physically active women (mean (SD); aged 24 (4) years, V ̇ O 2 peak ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{peak}}}}$ 39.3 (5.3) ml/kg/min) with (IUD; n = 19) and without (Control; n = 17) IUDs in the follicular and luteal phases of the menstrual cycle during light- and moderate-intensity exercise at fixed rates of heat production (∼175 and ∼275 W/m2 ) in 30°C, ∼21% relative humidity. Between-group and -phase differences were evaluated using traditional hypothesis testing and statistical equivalence testing within pre-determined bounds (±11 W/m2 ; difference required to elicit a ±0.3°C difference in core temperature over 1 h) in each exercise bout. Whole-body total heat loss was statistically equivalent between groups within ±11 W m-2 (IUD-Control [90% CIs]; Light: -2 [-8, 5] W/m2 , P = 0.007; Moderate: 0 [-6, 6] W/m2 , P = 0.002), as were dry and evaporative heat loss (P ≤ 0.023), except for evaporative heat loss during moderate-intensity exercise (equivalence: P = 0.063, difference: P = 0.647). Whole-body total and evaporative heat loss were not different between phases (P ≥ 0.267), but dry heat loss was 3 [95% CIs: 1, 5] W/m2 greater in the luteal phase (P ≤ 0.022). Despite this, all whole-body heat loss outcomes were equivalent between phases (P ≤ 0.003). These findings expand our understanding of the factors that modulate heat exchange in women and provide valuable mechanistic insight of the role of endogenous and exogenous female sex hormones in thermoregulation. KEY POINTS: Progestin released by hormonal intrauterine devices (IUDs) may negatively impact heat dissipation during exercise by blunting skin blood flow and sweating. However, the influence of IUDs on thermoregulation has not previously been assessed. We used direct calorimetry to show that IUD users and non-users display statistically equivalent whole-body dry and evaporative heat loss, body heat storage and oesophageal temperature during moderate- and high-intensity exercise in a warm, dry environment, indicating that IUDs do not appear to compromise exercise thermoregulation. However, within IUD users and non-users, dry heat loss was increased and body heat storage and oesophageal temperature were reduced in the luteal compared to the follicular phase of the menstrual cycle, though these effects were small and unlikely to be practically meaningful. Together, these findings expand our understanding of the factors that modulate heat exchange in women and have important practical implications for the design of future studies of exercise thermoregulation.

Progesterone and contraceptive progestin actions on the brain: A systematic review of animal studies and comparison to human neuroimaging studies.

In this review we systematically summarize the effects of progesterone and synthetic progestins on neurogenesis, synaptogenesis, myelination and six neurotransmitter systems. Several parallels between progesterone and older generation progestin actions emerged, suggesting actions via progesterone receptors. However, existing results suggest a general lack of knowledge regarding the effects of currently used progestins in hormonal contraception regarding these cellular and molecular brain parameters. Human neuroimaging studies were reviewed with a focus on randomized placebo-controlled trials and cross-sectional studies controlling for progestin type. The prefrontal cortex, amygdala, salience network and hippocampus were identified as regions of interest for future preclinical studies. This review proposes a series of experiments to elucidate the cellular and molecular actions of contraceptive progestins in these areas and link these actions to behavioral markers of emotional and cognitive functioning. Emotional effects of contraceptive progestins appear to be related to 1) alterations in the serotonergic system, 2) direct/indirect modulations of inhibitory GABA-ergic signalling via effects on the allopregnanolone content of the brain, which differ between androgenic and anti-androgenic progestins. Cognitive effects of combined oral contraceptives appear to depend on the ethinylestradiol dose.

Moving beyond the mean: Promising research pathways to support a precision medicine approach to hormonal contraception.

Women's psychological and behavioral responses to hormonal contraceptive (HC) treatment can be highly variable. One of the great challenges to researchers seeking to improve the experiences of women who use HCs is to identify the sources of this variability to minimize unpleasant psychobehavioral side-effects. In the following, we provide recommendations for programs of research aimed at identifying sources of heterogeneity in women's experiences with HC. First, we review research demonstrating person- and prescription- based heterogeneity in women's psychobehavioral responses to HCs. Next, we identify several promising person- and prescription- based sources of this heterogeneity that warrant future research. We close with a discussion of research approaches that are particularly well-suited to address the research questions raised in article. Together, this review provides researchers with several promising research pathways to help support the development of a precision medicine approach to HC treatment.

Hormonal contraceptive use is associated with differences in women's inflammatory and psychological reactivity to an acute social stressor.

Women using hormonal contraceptives (HCs) exhibit numerous signs of chronic inflammation, including elevated C-reactive protein levels and greater risk of developing mood and autoimmune disorders. However, users and non-users of HCs often have similar circulating proinflammatory cytokine levels, making the mechanism of association unclear. One possible explanation for this paradox is that HC users exhibit differences in their inflammatory responses to psychosocial stress that, over time, could contribute to chronic inflammation and its pathologies. Here, we tested this possibility by examining women's glucocorticoid, inflammatory, and psychological responses to the Trier Social Stress Test (TSST) in 67 naturally cycling (NC) and 60 oral HC-using women (Mage = 19.31, SDage = 1.95). As hypothesized, HC users and NC women exhibited different glucocorticoid and proinflammatory cytokine responses to the TSST. For NC women, TSST-induced increases in glucocorticoids were uncommon, and increases in glucocorticoids were accompanied by elevations in IL-6. In contrast, for women using HCs, increases in glucocorticoids in response to the TSST were common, and increases in glucocorticoids were accompanied by increases in TNF-α. HC users and NC women also differed in their psychological responses to the TSST, with HC users reporting elevated stress levels compared to NC women. Together, these results suggest that HC use impacts women's glucocorticoid, inflammatory, and psychological responses to psychosocial stress, potentially contributing to observed differences in these women's mental and physical health.

Levonorgestrel maintains goal-directed behavior in habit-trained intact female rats.

Hormonal contraceptives are utilized by millions of women worldwide. However, it remains unclear if these powerful endocrine modulators may alter cognitive function. Habit formation involves the progression of instrumental learning as it goes from being a conscious goal-directed process to a cue-driven automatic habitual motor response. Dysregulated goal and/or habit is implicated in numerous psychopathologies, underscoring the relevance of examining the effect of hormonal contraceptives on goal-directed and habitual behavior. This study examined the effect of levonorgestrel (LNG), a widely used progestin-type contraceptive, on the development of habit in intact female rats. Rats were implanted with subcutaneous capsules that slowly released LNG over the course of the experiment or cholesterol-filled capsules. All female rats underwent operant training followed by reward devaluation to test for habit. One group of females was trained at a level that is sub-threshold to habit, while another group of females was trained to a level well over the habit threshold observed in intact females. The results reveal that all sub-threshold trained rats remained goal-directed irrespective of LGN treatment, suggesting LNG is not advancing habit formation in female rats at this level of reinforcement. However, in rats that were overtrained well above the threshold, cholesterol females showed habitual behavior, thus replicating a portion of our original studies. In contrast, LNG-treated habit-trained rats remained goal-directed, indicating that LNG impedes the development and/or expression of habit following this level of supra-threshold to habit training. Thus, LNG may offset habit formation by sustaining attentional or motivational processes during learning in intact female rats. These results may be clinically relevant to women using this type of hormonal contraceptive as well as in other progestin-based hormone therapies.

Repeated exposure to physiologically effective doses of contraceptive hormones ethinyl estradiol or levonorgestrel do not alter the reinforcing effects of a brief visual stimulus in ovary-intact rats.

Estradiol and progesterone potentiate and attenuate reward processes, respectively. Despite these well-characterized effects, there is minimal research on the effects of synthetic estrogens (e.g., ethinyl estradiol, or EE) and progestins (e.g., levonorgestrel, or LEVO) contained in clinically-utilized hormonal contraceptives. The present study characterized the separate effects of repeated exposure to EE or LEVO on responding maintained by a reinforcing visual stimulus. Forty ovary-intact female Sprague-Dawley rats received either sesame oil vehicle (n = 16), 0.18 µg/day EE (n = 16), or 0.6 µg/day LEVO (n = 8) subcutaneous injections 30-min before daily one-hour sessions. Rats' responding was maintained by a 30-sec visual stimulus on a Variable Ratio-3 schedule of reinforcement. The day after rats' last session, we determined rats estrous cycle phase via vaginal cytology before sacrifice and subsequently weighing each rat's uterus to further verify the contraceptive hormone manipulation. The visual stimulus functioned as a reinforcer, but neither EE nor LEVO enhanced visual stimulus maintained responding. Estrous cytology was consistent with normal cycling in vehicle rats and halting of normal cycling in EE and LEVO rats. EE increased uterine weights consistent with typical uterotrophic effects observed with estrogens, further confirming the physiological impacts of our EE and LEVO doses. In conclusion, a physiologically effective dose of neither EE nor LEVO did not alter the reinforcing efficacy of a visual stimulus reinforcer. Future research should characterize the effects of hormonal contraceptives on responding maintained by other reinforcer types to determine the generality of the present findings.

Adaptive Calibration of Dyadic Sexual Desire Is Sex Differentiated and Disrupted by Hormonal Contraceptives.

Adaptive calibration models suggest that features of people's childhood ecologies can shape their reproductive outcomes in adulthood. Given the importance of dyadic sexual desire (i.e., desire for sex with a partner) for relationships and reproduction, we examined the extent to which people's childhood ecologies-especially the unpredictability of those ecologies-adaptively calibrate such desire. Nevertheless, because female (versus male) sexual desire is presumed to be more sensitive to situational factors, and because hormonal contraceptives alter myriad aspects of female physiology that influence female sexual desire, we predicted that adaptive calibration of dyadic sexual desire would emerge more strongly for naturally cycling females (versus females who use hormonal contraceptives and versus males). In Study 1, a total of 630 participants (159 males, 203 naturally cycling females, and 268 females using hormonal contraceptives) completed questionnaires assessing the harshness and unpredictability of their childhood ecologies as well as their sexual desire. Consistent with predictions, childhood unpredictability (but not harshness) was positively associated with dyadic (but not solitary) sexual desire among naturally cycling females (but not among females using hormonal contraceptives nor among males). Study 2, which consisted of 736 females (307 naturally cycling females, 429 females using hormonal contraceptives), replicated this pattern of results for females. These findings add to a growing literature suggesting that the instability of people's early childhood ecologies can adaptively calibrate their adult reproductive motivations and behaviors, including their dyadic sexual desire. Not only is the current finding among the first to show that some adaptive calibration processes may be sex differentiated, it further highlights that hormonal contraceptives, which alter the evolved reproductive physiology of females, may disrupt adaptive calibration processes (though such disruption may not be inherently negative).

Relationship between classic indicators of health behaviour and contraceptive choices in women in Flanders.

BACKGROUND: In this study we shed light on ongoing trends in contraceptive use in Flanders (Belgium). Building on the fundamental cause theory and social diffusion of innovation theory, we examine socio-economic gradients in contraceptive use and the relationship to health behaviours. METHODS: Using the unique and recently collected (2020) ISALA data, we used multinomial logistic regression to model the uptake of contraceptives and its association to educational level and health behaviour (N:4316 women). RESULTS: Higher educated women, and women with a healthy lifestyle especially, tend to use non-hormonal contraceptives or perceived lower-dosage hormonal contraceptives that are still trustworthy from a medical point of view. Moreover, we identified a potentially vulnerable group in terms of health as our results indicate that women who do not engage in preventive health behaviours are more likely to use no, or no modern, contraceptive method. DISCUSSION: The fact that higher educated women and women with a healthy lifestyle are less likely to use hormonal contraceptive methods is in line with patient empowerment, as women no longer necessarily follow recommendations by healthcare professionals, and there is a growing demand for naturalness in Western societies. CONCLUSION: The results of this study can therefore be used to inform policy makers and reproductive healthcare professionals, since up-to-date understanding of women's contraceptive choices is clearly needed in order to develop effective strategies to prevent sexually transmitted infections and unplanned pregnancies, and in which women can take control over their sexuality and fertility in a comfortable and pleasurable way.

Exploring the relationship between contraceptive medication use and concussion recovery in female collegiate athletes: a LIMBIC MATARS consortium investigation.

OBJECTIVE: While recovery from concussion is variable, women are more likely to report symptoms, experience worse outcomes, and have longer recovery trajectories following concussion than men. Preliminary data suggest that hormonal fluctuations, specifically progesterone, may be associated with this variability. This study aimed to understand the effect of contraceptive medication on concussion recovery. METHODS: A retrospective chart review using consensus-based common data elements was conducted at 11 NCAA institutions as part of the LIMBIC MATARS consortium. Participants included female collegiate athletes diagnosed with a concussion who did (n = 117) or did not report (n = 339) contraceptive medication use. Number of days between diagnosis and symptom resolution were compared using Mann-Whitney U tests. Self-reported diagnosis of attention deficit hyperactivity disorder, concussion history, anxiety, and depression was compared using Chi-squared tests. RESULTS: The proportions of participants who did or did not take contraceptive medication were similar across covariates. Female athletes regardless of contraceptive medication use recovered similarly following a concussion. CONCLUSIONS: Our findings suggest that contraceptive medication use did not significantly impact concussion recovery. Future prospective investigations should examine documentation practices and operationalize terminology for hormonal contraceptive medication to better understand their role on recovery from sport-related concussion in female collegiate athletes.

Auditing the representation of hormonal contraceptives in studies assessing exercise performance in women.

Hormonal contraceptive (HC) users have a different ovarian hormonal profile compared to eumenorrheic women. Due to the prevalence of HC use amongst sportswomen, there has been increased research efforts to understand their impact on exercise performance. The aim was to audit this research. Studies identified were assessed for HC type, athlete calibre, performance outcome, study design, and quality of methodological control regarding ovarian hormonal profiles. Sixty-eight different HCs were reported across 61 studies. Monophasic combined oral contraceptive (OCP) pills represented 60% of HCs, followed by other pills [34%, phasic-combined, progestogen-only, and un-specified], phasic and long acting reversible contraceptives [5%, vaginal ring, patch, implant, injection, intrauterine system] and unspecified HCs (1%). Eleven percent of participants using HCs were classified as highly trained or elite/international with no participants being classed as world class. Whilst the number of studies involving HCs has increased two-fold over the past decade, the number of studies ranked as gold standard has not increased (HC; 2003-57%, 2011-55%, 2022-43%. OCP; 2003-14%, 2011-17%, 2022-12%). Future research assessing HCs and exercise performance should adopt high-quality research designs and include a broader range of HCs in highly trained to world-class populations to increase the reach and impact of research in this area.

Oral manifestations in women using hormonal contraceptive methods: a systematic review.

OBJECTIVES: To investigate the oral manifestations in women of reproductive age using hormonal contraceptive methods. MATERIALS AND METHODS: This review is based on the PRISMA statement. A literature search incorporated observational studies from the last 21 years. An investigative question was formulated using the PICO model, studies were selected, and a quality analysis was performed using the modified STROBE guidelines. A bibliometric analysis was performed, and the data were examined. RESULTS: Thirteen articles were included, with the majority evaluating periodontal status. Others analyzed factors such as the presence of alveolar osteitis, oral candidiasis, and salivary microbiome dysbiosis. Ten articles were deemed to have a low risk of bias. CONCLUSIONS: Hormonal contraceptives may increase the risk of alveolar osteitis following tooth extraction and increase the presence of the Candida species in the oral cavity. They also affect the periodontium, such as the frequent development of gingivitis, but do not lead to changes in the salivary microbiome. CLINICAL RELEVANCE: The increasing number of women using hormonal contraceptives and the knowledge that these contraceptives can produce oral cavity alterations underscore the need to evaluate the oral manifestations found in these women.

The male birth control pill - A new approach to family planning and population control.

With the increase in the world's population, contraception is crucial in population control strategies. Majority of contraceptives produced today are targeted at women; many of whom experience side effects, leading to the discontinuation of these contraceptives after a year of use. As the use of condoms and vasectomies has been subjected to scrutiny, it is necessary for the development of male birth control (BC). Attempts to achieve this include hormonal and non-hormonal contraception. Hormonal contraception prevents the production of the sperm in the testes; but this mode of BC has been found to be ineffective while also causing behavioural changes in men. In contrast, non-hormonal male contraception focuses on rendering the sperm immotile to prevent fertilization post-copulation. Soluble adenylate cyclase is an area of research that has shown promise in this field. Furthermore, two inhibitors, TDI-10299 and TDI-11861, have been developed and tested, with the latter, showing greater potency and longer activity, in mice models. Overall, by developing non-hormonal male contraceptives, men will have more control over their reproductive health. Nonetheless, before such contraceptives can be made widely available, it is important that further research takes place to ensure the safety and effectiveness of these methods.

Assessing the impact of hormonal contraceptive use on menstrual health among women of reproductive age - a systematic review.

BACKGROUND: Contraceptive methods are well-established in their ability to prevent pregnancy and increase individual agency in childbearing. Evidence suggests that contraceptives can also be used to treat adverse conditions associated with menstruation, including abnormal and prolonged uterine bleeding, heavy menstrual bleeding, painful menstruation, endometriosis, uterine fibroids, and premenstrual dysphoric disorders.This review investigates the effects of contraceptive techniques such as contraceptive pills, and long-acting reversible contraceptives (e.g. intrauterine devices, implants) on menstrual morbidity. METHODS: Over ten databases with no geographical boundaries were searched from inception until October 2023. Study designs were one of the following types to be included: parallel or cluster randomised controlled trials, controlled clinical trials, controlled before and after studies, interrupted time series studies, cohort or longitudinal analyses, regression discontinuity designs, and case-control studies. Ten team members screened the papers in pairs with a Kappa score of more than 7, and Covidence was used. Conflicts were resolved by discussion, and the full papers were divided among the reviewers to extract the data from eligible studies. RESULTS: Hormonal contraceptives are considered a well-tolerated, non-invasive, and clinically effective treatment for abnormal and prolonged uterine bleeding, heavy menstrual bleeding, painful menstruation, endometriosis, uterine fibroids, and premenstrual dysphoric disorders. Our studies investigating quality of life or well-being in women with heavy menstrual bleeding, endometriosis, or uterine fibroids have found improvements in all dimensions assessed. CONCLUSIONS: Hormonal contraceptives significantly reduce pain, symptom severity, and abnormal bleeding patterns associated with women who suffer from heavy menstrual bleeding, endometriosis, and uterine fibroids.

Hormonal contraceptives significantly reduce pain, symptom severity, and abnormal bleeding patterns associated with women who suffer from heavy menstrual bleeding, endometriosis, and uterine fibroids. Findings can inform clinical practice and policy decisions to ensure that women have access to safe and effective contraceptive options that promote both reproductive and non-reproductive health.

Correlation of sexual desire with sexual hormone binding globulin and free androgen index in women using combined contraceptives.

PURPOSE: To correlate the sexual desire levels with sexual hormone binding globulin and free androgen index in women taking different types of hormonal contraceptives (HCs) containing ethinylestradiol (EE), oestradiol valerate (E2V), 17ß-oestradiol (E2), or estetrol (E4), combined or in phasic formulation with different progestogens having antiandrogenic properties. METHODS: Three hundred and sixty-seven women (age range 18-46) participated in the study. SHBG and total testosterone (TT) were measured, and the Free Androgen Index (FAI) was calculated. The Female Sexual Function Index (FSFI) and the Female Sexual Distress Scale (FSDS) questionnaires were used to assess sexual function and distress, respectively. RESULTS: The highest SHBG values and the lowest FAIs were obtained of women on HCs containing EE than those of women on HCs containing E2V/17ß E2 or E4 (p < 0.001). Desire scores and FSFI total scores were lower in women on HCs with EE than in those using HCs containing E2V, 17ß E2, or E4 (p ≤ 0.001). The women who were on HCs containing EE reported FSDS levels higher than those containing all the other types of oestrogen. Finally, sexual desire and FSFI total scores had a negative correlation with the SHBG values and a positive correlation with FAI percentage (p ≤ 0.0001). CONCLUSIONS: A minority of women using HCs with EE might experience a decreased sexual desire. This was not observed in women on HCs containing E2V, 17 E2, or E4. To avoid HC discontinuation, due to sexual desire reduction, HCs having minor antiandrogenic effects could be taken into consideration.

Methods and considerations for the use of hormonal contraceptives in rat models of neurobehavior.

Hormonal contraceptives (HCs), prescribed to millions of women around the world, alter the ovarian hormonal cycle resulting in neurobehavioral changes in HC users. Human epidemiological and experimental data has characterized some of these effects with oftentimes conflicting or irreproducible results, reflecting a dearth of research considering different compositions, routes of administration, or time-courses of HC use. Non-human animal research can model these effects and help elucidate the underlying mechanisms by which different HCs modulate neurobehavioral outcomes. Still, animal models using HCs are not well-established. This may be because the pharmacological profile of HCs - including the metabolism, receptor binding affinity, and neuromodulatory effects - is dynamic and not always clearly translatable between animals and humans. The current review addresses these issues and provides basic methods and considerations for the use of HCs in animal models of neurobehavior to help advance the field of behavioral neuroendocrinology and inform decisions regarding to women's health.

What is there to know about the effects of progestins on the human brain and cognition?

Progestins are an important component of hormonal contraceptives (HCs) and hormone replacement therapies (HRTs). Despite an increasing number of studies elucidating the effects of HCs and HRTs, little is known about the effects of different types of progestins included in these medications on the brain. Animal studies suggest that various progestins interact differently with sex steroid, mineralocorticoid and glucocorticoid receptors and have specific modulatory effects on neurotransmitter systems and on the expression of neuropeptides, suggesting differential impacts on cognition and behavior. This review focuses on the currently available knowledge from human behavioral and neuroimaging studies pooled with evidence from animal research regarding the effects of progestins on the brain. The reviewed information is highly relevant for improving women's mental health and making informed choices regarding specific types of contraception or treatment.

Modeling hormonal contraception in female rats: A framework for studies in behavioral neurobiology.

Research on hormonal contraceptives (HC) in animal models is lacking, and as a result, so is our understanding of the impact of HC on the brain and behavior. Here, we provide a review of the pharmacology of HC, as well as the methodology and best practices for designing a model of HC in female rats. We outline specific methodological considerations regarding dosing, route of administration, exposure time/timing, and selecting a control group. We also provide a framework outlining important levels of analysis for thinking about the impact of HC on behavioral and neurobiological outcomes. The purpose of this review is to equip researchers with foundational knowledge, and some basic elements of experimental design for future studies investigating the impact of HC on the brain and behavior of female rats.

Combined oral contraceptive use and risk for binge eating in women: Potential gene × hormone interactions.

Extant animal and human data suggest endogenous ovarian hormones increase risk for binge eating in females, possibly via gene × hormone interactions and hormonally induced increases in genetic influences. Approximately 85 % of women will take combined oral contraceptives (COCs) that mimic the riskiest hormonal milieu for binge eating (i.e., post-ovulation when both estrogen and progesterone are present). The purpose of this narrative review is to synthesize findings of binge eating risk in COC users. Few studies have been conducted, but results suggest that COCs may increase risk for binge eating and related phenotypes (e.g., craving for sweets), particularly in genetically vulnerable women. Larger, more systematic human and animal studies of COCs and binge eating are needed. The goal of this work should be to advance personalized medicine by identifying the extent of COC risk as well as the role of gene × hormone interactions in susceptibility.

How hormonal contraceptives shape brain and behavior: A review of preclinical studies.

Steroid hormones influence different aspects of brain function, including development, neurogenesis, neuronal excitability, and plasticity, thus affecting emotional states, cognition, sociality, and reward. In women, their levels fluctuate across the lifespan and through the reproductive stages but are also altered by exogenous administration of hormonal contraceptives (HC). HC are widely used by women throughout their fertile life both for contraceptive and therapeutic benefits. However, awareness of their effects on brain function and behavior is still poorly appreciated, despite the emerging evidence of their action at the level of the central nervous system. Here, we summarize results obtained in preclinical studies, mostly conducted in intact female rodents, aimed at investigating the neurobiological effects of HC. HC can alter neuroactive hormones, neurotransmitters, neuropeptides, as well as emotional states, cognition, social and sexual behaviors. Animal studies provide insights into the neurobiological effects of HC with the aim to improve women's health and well-being.

Hormonal contraceptives as disruptors of competitive behavior: Theoretical framing and review.

Emerging evidence suggests that hormonal contraceptives (HCs) impact psychological outcomes through alterations in neurophysiology. In this review, we first introduce a theoretical framework for HCs as disruptors of steroid hormone modulation of socially competitive attitudes and behaviors. Then, we comprehensively examine prior research comparing HC users and non-users in outcomes related to competition for reproductive, social, and financial resources. Synthesis of 46 studies (n = 16,290) led to several key conclusions: HC users do not show the same menstrual cycle-related fluctuations in self-perceived attractiveness and some intrasexual competition seen in naturally-cycling women and, further, may show relatively reduced status- or achievement-oriented competitive motivation. However, there a lack of consistent or compelling evidence that HC users and non-users differ in competitive behavior or attitudes for mates or financial resources. These conclusions are tentative given the notable methodological limitations of the studies reviewed. Implications and recommendations for future research are discussed.